Sales at John Lewis dropped 14% for the week to November 15, with fashion sales also taking a downturn following comparatively mild weather.
Selling operations director Nat Wakely said that fashion sales had also dipped: "Women's fashion has been slow, which we're putting down to the weather - we haven't really had last year’s cold snap, so coats, hats and scarves are not selling as well.
He added: "Kidswear is performing better. Fashion fabrics and haberdashery is continuing to be strong. We won’t match our record Christmas last year but December will be better than November."
Wakely added that the overall sales dip was against difficult comparisons, which included the first week’s trading at the new John Lewis store in Cambridge and an online Waitrose promotion.
"Without those factors the figure is more like 10%, which is line with the previous five weeks," he said.
Last week, the department store group said that sales were down 9.7% for the previous week, to November 8.